The production of fibers from thermoplastic synthetic resin is useful to produce mats or webs of such fibers with a high fluid permeability and capacity for use wherever nonwoven fabrics or fiber mats or fleeces are desirable.
In general an apparatus for producing such webs, e.g. by a melt-blowing process, may have a fiber-producing head with orifices from which the molten synthetic resin emerges.
Fiber-generating heads may also be used for other purposes. In general a device for the production of fiber or thermoplastic synthetic resins of the type with which the invention is concerned, can comprise at least one melt passage through which a molten synthetic resin is fed and at least one nozzle having an outlet end provided with a nozzle orifice from which the molten synthetic resin emerges.
The nozzle orifices may be bores which are formed directly at the tip of the nozzle or at least at a discharge side thereof. In the past, it has been customary to provide a single row of such nozzle bores or orifices at the nozzle tip. This greatly limits the density of the nozzle bores or orifices, i.e. the number of such bores or orifices per unit length or area. In many cases the density of the nozzle passages or the orifice density was smaller than 35 orifices per cm. As a general matter, moreover, the drilling of the nozzle is a very expensive procedure as is the preparation of a multiplicity of nozzles with different orifice densities and their substitution in a fiber-blowing head. As a result, such devices and fiber-blowing heads have not been fully satisfactory in the past.